Single well combination oil production/water dump flood apparatus and methods

ABSTRACT

A subterranean well production system utilizes a single well to perform both hydrocarbon fluid production and water dumpflooding processes. The well has a primary wellbore that is communicated with first and second subterranean zones respectively containing hydrocarbon fluid and higher pressure water. A second, lateral wellbore extends from the primary wellbore and communicates with the first zone. A remotely controllable routing system, including a valved production tubing structure extending through the primary wellbore, is operable to (1) flow hydrocarbon fluid from the first zone to the surface via the production tubing and (2) simultaneously dumpflood water from the second zone into the first zone, via the production tubing, to increase the pressure within the first zone and thereby increase the hydrocarbon fluid production rate.

TECHNICAL FIELD

[0001] The present invention relates generally to apparatus and methods for the production of hydrocarbon fluids and, in single well embodiments described herein, more particularly provides specially designed combination hydrocarbon production dump flood apparatus and associated methods.

BACKGROUND

[0002] In the recovery of hydrocarbon products, such as oil and/or gas, from subterranean formations it is frequently necessary at some time subsequent to the onset of recovery to accelerate the recovery process by increasing the pressure in the hydrocarbon-bearing formation to compensate for an unavoidable pressure decrease therein caused by the removal of fluids from the formation. A known method of providing this desirable formation pressure increase is to inject fluids—water or gas—into the subterranean formation using dedicated injection wells, while producing hydrocarbons from the subterranean formation using dedicated production wells. An alternate method using this principle is to utilize two separate wells—(1) an oil producing well extending through an oil-bearing subterranean formation, and (2) a dumpflood well, which is typically a work-over of an existing well which permits a downhole cross flow of water or gas from an overlying or underlying aquifer or gas cap into the oil producing zone for pressure maintenance purposes.

[0003] While this conventional secondary recovery technique of providing, via a first well, water-based pressure stimulation of an oil-producing subterranean formation intersected by a second well is widely used, it undesirably adds considerable expense to the overall oil recovery process, and is normally uncontrolled, although monitoring is achievable by regular intervention for production logging. As can be readily seen, it would be desirable to provide improvements in this general secondary recovery technique. It is to this goal that the present invention is primarily directed.

SUMMARY

[0004] In carrying out the principles of the present invention, in accordance with an embodiment thereof, a subterranean fluid production system is provided in which water dumpflooding-enhanced hydrocarbon production may be economically carried out utilizing a single well which is created by forming intersecting first and second wellbores, communicating the first wellbore with a hydrocarbon-containing subterranean zone and a subterranean aquifer, and communicating the second wellbore with the hydrocarbon-containing subterranean zone at some distance from the first wellbore. In the completed well, hydrocarbon fluid is flowed to the surface sequentially through the second and first wellbores, and the pressure in the hydrocarbon-containing zone is increased, to thereby accelerate the hydrocarbon fluid production rate, by forcing water from the aquifer into the hydrocarbon-containing zone through the first wellbore.

[0005] While the well described below and illustrated in the accompanying drawings is representatively used to produce oil, and water is used as a pressure-boosting secondary recovery fluid, principles of the invention could also be advantageously utilized in conjunction with other subterranean production and recovery fluids if desired.

[0006] In a representative structural embodiment of the well, a tubing string extends through the first wellbore, which itself extends through the production fluid (oil)-containing zone and the recovery fluid (water)-containing zones, and defines with the first wellbore an annulus circumscribing the tubing string. A longitudinally spaced plurality of sealing structures, such as packers, circumscribe the tubing string, are disposed in the annulus, and form in the annulus first and second sealed off annulus intervals, with a third interior portion of the first wellbore being disposed downhole of the first and second annulus intervals and communicated with the interior of the tubing string. The second wellbore, representatively a secondary lateral wellbore, extends outwardly from the first or primary wellbore and intercommunicates the first annulus interval with the production fluid-containing zone.

[0007] A first valve, representatively a production interval control valve, is connected in a portion of the tubing string disposed within the first annulus interval and is operable to selectively communicate the interior of the tubing string with the first annulus interval. A second valve, representatively a production/dumpflood isolation valve, is connected in a portion of the tubing string disposed within the first annulus interval downhole from the first valve, the second valve being operable to selectively permit and preclude fluid flow through the tubing string past the second valve. A third valve, representatively a dumpflood control valve, is connected in the portion of the tubing string disposed within the second annulus interval, the third valve being operable to selectively communicate the interior of the tubing string with the second annulus interval.

[0008] A first sidewall opening is formed in the first wellbore at the second annulus interval and intercommunicates one of the production fluid-containing and recovery fluid-containing zones with the second annulus interval. A second sidewall opening is formed in the first wellbore and intercommunicates the other of the production fluid-containing and recovery fluid-containing zones with the third interior portion of the first wellbore.

[0009] In an alternate embodiment of the well, a pump is operatively installed in a portion of the tubing string disposed in the second annulus interval and is operable to boost the pressure of the recovery fluid forced into the production fluid-containing zone.

[0010] The interiors of the first wellbore and the tubing string define a flow path extending through the first wellbore and having first and second portions. The various valves, sealing devices and openings incorporated in the first wellbore function as an overall routing system which is associated with the flow path and is operable to (1) selectively cause production fluid to be flowed sequentially from the production fluid-containing subterranean zone into and through the first flow path portion to the surface, and/or (2) selectively cause recovery fluid from the recovery fluid-containing subterranean zone to flow into the production fluid-containing zone via the second flow path portion.

[0011] Illustratively, at least a portion of this routing system is remotely controllable. Additionally, the well completion may also include a sensor structure operative to sense the pressures and temperatures in the second annulus interval and within the tubing string downhole of the second valve and transmit the sensed pressure and temperature levels to the surface. These sensed pressure and temperature levels may be utilized to control at least a portion of the routing system—either manually or automatically.

[0012] The ability provided by the present invention to utilize a single well to provide both fluid production and associated dumpflooding to accelerate the fluid production rate yields a substantial reduction in well capital expenditure for new drill applications, and can also significantly reduce operating expenses by eliminating the requirement for intervention to monitor and/or control the well performance.

[0013] These and other features, advantages and benefits of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a simplified, somewhat schematic cross-sectional view through a portion of a single subterranean well embodying principles of the present invention and utilized to perform both production and dumpflooding functions in conjunction with separate subterranean production and recovery fluid-bearing zones;

[0015]FIG. 2 is a view similar to that in FIG. 1, but with the relative vertical orientations of the productions and recovery fluid-bearing zones being reversed; and

[0016]FIG. 3 is a view similar to that in FIG. 1, but illustrating an alternative embodiment of the well with a dumpflooding pump structure being operatively incorporated therein.

DETAILED DESCRIPTION

[0017] Representatively illustrated in simplified, somewhat schematic cross-sectional form in FIG. 1 is a portion of a single subterranean well 10 which embodies principles of the present invention and forms a portion of an overall subterranean fluid production system 11. In the following description of the well 10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.

[0018] The illustrated portion of the overall single well 10 shown in FIG. 1 extends through a section of the earth 12 which contains a production fluid-bearing zone 14 (the production fluid representatively being oil) spaced downwardly apart from a separate recovery fluid-bearing zone 16 (the recovery fluid representatively being water). Illustratively, the recovery fluid-bearing zone 16 has a higher internal pressure than that present in the production fluid-bearing zone 14, and the zones 14,16 slope upwardly and to the right as viewed in FIG. 1. However, the zones 14,16 could be oriented differently. Moreover, at least in an initial period of hydrocarbon fluid recovery of the single well 10, the zone 16 could have a lower internal pressure than that of the zone 14.

[0019] Well 10 includes a representatively vertical primary wellbore 18 which intersects both of the zones 14 and 16. Wellbore 18 illustratively is a cased wellbore, having a metal casing 20 cemented-in, as at 22, in a conventional manner. Alternatively, the wellbore 18 could be of an uncased type without departing from principles of the present invention. Intersecting the primary wellbore 18, at a window location 24 above the main wellbore's intersection with the zone 16, is a downwardly sloping lateral or secondary wellbore 26 which is internally lined, as at 28. Lateral wellbore 26 is formed in a conventional manner after the formation of the primary wellbore 18, intersects the two zones 14 and 16, and has an open inlet end 30 disposed within an upper portion 14 a of the zone 14 and operatively connected to a suitable inlet filter 32. It is to be understood, however, that the inlet filter 32 is not necessary in keeping with the principles of the invention.

[0020] A length of production tubing 34, having a smaller diameter than that of the casing 20, coaxially extends downwardly through the interior of the primary wellbore 18 from the earth's surface and has an open lower end 34 a representatively positioned within a lower portion 14 b of the zone 14. An annulus 36 is defined between the interior side surface of the casing 20 and the exterior side surface of the production tubing 34.

[0021] Various conventional isolation, flow control and sensing components are operatively installed in the production tubing 34, as schematically depicted in FIG. 1, within the primary wellbore 18. From top to bottom in FIG. 1, these components include a production packer 38; a production interval control valve 40; a production/dumpflood isolation valve 42; a production/dumpflood isolation packer 44; a pressure/temperature sensor structure 46; a dumpflood control valve 48; and a dumpflood isolation packer 50. The flow control and sensing components 40, 42, 46 and 48 are remotely controllable from the surface via a schematically depicted control line structure 52 extending through the annulus 36.

[0022] Packers 38 and 44 seal off within the annulus 36 a longitudinal annulus interval 36 a which extends between the packers 38,44 and is upwardly spaced apart from the portion of the subterranean zone 16 penetrated by the primary wellbore 18. Annulus interval 36 a communicates with the portion 14 a of the subterranean zone 14 via the lateral secondary wellbore 26. Packers 44 and 50 seal off within the annulus 36 a longitudinal annulus interval 36 b which extends between the packers 44 and 50, straddles the subterranean zone 16, and is disposed above the portion of the subterranean zone 14 penetrated by the primary wellbore 18.

[0023] Perforations 54 extend through the casing 20, representatively via a suitable casing screen structure 56, and communicate the subterranean zone 16 with the casing interval 36 b. Additionally, perforations 58 extend through the casing 20 and communicate the portion 14 b of the subterranean zone 14 with a portion 36 c of the annulus 36 beneath the sealed-off casing interval 36 b.

[0024] Interval control valve 40 may be opened or closed from a remote location to selectively communicate the portion 14 a of the subterranean zone 14 with the interior of the production tubing 34, via the lateral wellbore 26, or isolate the zone portion 14 a from the production tubing 34. Isolation valve 42 is representatively a normally closed ball valve, but could be one of a variety of other suitable types of valves, and may be opened to provide access through the production tubing 34 to the various tubing string components below the valve 42. Sensor structure 46 is operative to monitor the adjacent pressures and temperatures within the annulus interval 36 b and the production tubing interior and transmit the sensed pressure and temperature values to the surface, via the control line structure 52, to enable the manual or automatic control of the valves 40, 42 and 48. Dumpflood control valve 48 is selectively operable to communicate the annulus interval 36 b with the interior of the production tubing 34 or isolate the annulus interval 36 b from the interior of the production tubing 34.

[0025] The single well 10 may be constructed as a new well as schematically depicted in FIG. 1, or may initially be an existing well (having only the primary wellbore 18) which is subsequently worked over to add the lateral or secondary wellbore 26 and the illustrated and previously described isolation, flow control and sensing components operatively incorporated in the production tubing string 34. In either event, the single well 10 advantageously provides (without the previous necessity of providing a second well to operate in conjunction therewith) the capability of simultaneously carrying out both a hydrocarbon fluid recovery process and a water dumpflooding process (also commonly referred to as simply a “water flooding” or “injection” process) to raise the pressure within the zone 14 and thereby increase the production rate of zone 14.

[0026] To illustrate the operation of the single well 10 it will be assumed for purposes of discussion that the initial pressure within the production fluid-bearing zone 14 is sufficient to provide a satisfactory rate of production therefrom of the desired hydrocarbon fluid such as oil 60. In this event, the production interval control valve 40 is set to its open position, and the valves 42 and 48 below the valve 40 are set to their closed positions. This precludes the separate subterranean zones 14,16 from communicating with one another via either the production tubing 34 or the annulus 36, while at the same time communicating the upper portion 14 a of the zone 14 with the interior of the production tubing 34, above the closed valve 42, via the interior of the lateral wellbore 26, the annulus interval 36 a and the open production interval control valve 40. Accordingly, oil 60, solely by virtue of the pressure within the zone 14, is flowed to the surface sequentially through the lateral wellbore 26, the annulus interval 36 a, the open valve 40, and the interior of the production tubing 34.

[0027] When, after a period of oil production carried out in this manner, the pressure within the zone 14 falls to a predetermined level below the pressure in the zone 16 (as detected by the sensor structure 46 and relayed to the surface via the control line structure 52) the dumpflood control valve 48 is opened—either manually or automatically according to the particular control technique being employed. In response to the opening of the valve 48, water 62 within the zone 16 flows into the casing interval 36 b through the casing perforations 54, flows inwardly through the opened valve 48 and enters the interior of the portion of the production tubing 34 beneath the closed valve 42. The water 62 then flows downwardly through this lower production tubing portion, out its open lower end 34 a and into the lower portion 14 b of the zone 14 via the casing perforations 58.

[0028] Water 62 being forced into the zone portion 14 b in this dumpflooding portion of the overall production method elevates the pressure within the zone 14, forces the oil 60 toward the upper portion 14 a of the zone 14 due to the density difference between the oil 60 and the dumpflooded water 62, and desirably increases the production flow rate of the oil 60 through the lateral wellbore 26.

[0029] Thus, as schematically depicted in FIG. 1, in the illustrated subterranean fluid production system 11 both oil production and dumpflooding capabilities are provided in the single well 10—no auxiliary second well is required. It can be seen that the production tubing 34 and the annulus 36 define within the primary wellbore 18 a flowpath which extends therethrough and has a first longitudinal portion above the packer 44, and a second longitudinal portion below the packer 44. Previously described components (such as the packers, valves and casing perforations) associated with this flow path function as what may be termed routing structure operable to (1) selectively permit production fluid (representatively the oil 60) to be flowed sequentially from the zone 14 into the lateral wellbore 26, through the wellbore 26 into the first flowpath portion, and then to the surface via the first flowpath portion, and/or (2) selectively permit recovery fluid (representatively water 62) from the zone 16 to flow into the zone 14 via the second longitudinal flowpath portion.

[0030] While the operation of the subterranean fluid production system 11 schematically depicted in FIG. 1 has been representatively described based on the assumption that the initial pressure within the zone 14 was sufficiently high to permit oil production without initially utilizing the auxiliary water dumpflooding capability of the single well 10, it will be readily appreciated by those of skill in this particular art that the initial pressure within the zone 14 may be both lower than that within the zone 16 and too low to sustain a satisfactory production flow rate. In this instance, of course, water dumpflooding could be utilized during even the initial phase of oil production flow from the well, and artificial lift or conventional pumping methods may be used to assist the flow of production fluid to the surface at a satisfactory rate.

[0031] Schematically illustrated in FIG. 2 is an alternate embodiment 11 a of the previously described subterranean fluid production system 11. In the system embodiment 11 a the production fluid-bearing zone 14 is disposed above the recovery fluid-bearing zone 16 instead of below it. Accordingly, the lateral wellbore 26 does not extend through the zone 16 before entering the zone 14. Otherwise, the structure of the single well 10 in the system 11 a is identical to that of the single well 10 incorporated in the system 11 shown in FIG. 1.

[0032] During simultaneous production and water dumpflooding operations of the system 11 a, with the valves 40 and 48 opened and the valve 42 closed, the oil flow production route is identical to that previously described in conjunction with the FIG. 1 system 11. Namely, oil 60 from the zone 14 flows into the lateral wellbore 26 through the inlet screen 32, through the lateral wellbore 26 into the annulus interval 36 a, into the production tubing 34 through the opened interval control valve 40, and then upwardly through the production tubing 34 to the surface.

[0033] However, in the system 11 a the water dumpflood flow direction is reversed relative to the dumpflood flow direction in the system 11 a due to the location of the zone 16 below the zone 14. Specifically, as shown in FIG. 2, water 62 in zone 16 (at a higher pressure than the internal pressure within the zone 14) sequentially flows via the casing perforations 58 into the casing annulus 36 below the packer 50, upwardly into the interior of the production tubing 34 through its open lower end 34 a, upwardly through the production tubing 34 to the opened dumpflood valve 48, outwardly through the valve 48 into the annulus interval 36 b, and then outwardly into the portion 14 b of the zone 14 via the casing perforations 54 to boost the internal pressure within the zone 14 and increase the production flow rate of the oil 60.

[0034] A second alternate embodiment 11 b of the previously described subterranean fluid production system 11 is schematically depicted in FIG. 3. System 11 b is identical in structure and operation to the system 11 with the exception that a schematically depicted pump 64 is operatively installed in the production tubing 34 between the dumpflood valve 48 and the packer 50. Pump 64 functions to boost the pressure of dumpflood water 62 within the production tubing 34 before the water 62 is forced into the portion 14 b of the zone 14 through the casing perforations 58. The pump 64 is appropriately linked to the control line structure 52 so that the pump 64, like other routing structure components associated with the wellbore 18, may be remotely controlled—either manually or automatically. In the event that the zone 14 is disposed above the zone 16 (as shown in FIG. 2), the pump 64 is simply reoriented in the production tubing 34 so that the flow direction of the pump 64 is reversed to create a corresponding dumpflood water flow direction reversal as shown in FIG. 2.

[0035] While the systems 11, 11 a and 11 b have been representatively illustrated with oil as their production fluid and water as their pressure boosting recovery fluid, it will be readily appreciated by one of ordinary skill in this particular art that the systems could be alternatively utilized in conjunction with other production and recovery fluids if desired. For example, water from a first subterranean zone could be dumpflooded into a second subterranean zone to produce gas, or gas from a first subterranean zone could be forced into a second subterranean zone to enhance the production rate of oil therefrom. Principles of the present invention may also be employed in similar situations where dumpflooded water is utilized to provide enhanced sweep efficiency, and may be utilized to provide gas injection for pressure maintenance or flooding to enhance sweep efficiencies.

[0036] Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims. 

What is claimed is:
 1. A subterranean fluid production system comprising: a first subterranean zone containing a recoverable production fluid; a second subterranean zone containing a recovery fluid flowable into the first zone to increase the pressure therein; and a well including: a first wellbore communicated with each of the first and second zones, a second wellbore extending outwardly from the first wellbore and communicating it with the first zone, a flow path extending through the first wellbore and having first and second portions, and routing structure associated with the flow path and operable to (1) selectively cause production fluid to be flowed sequentially from the first zone into and through the first flow path portion to the surface, and/or (2) selectively cause recovery fluid from the second zone to flow into the first zone via the second flow path portion.
 2. The subterranean fluid production system of claim 1 wherein the production fluid is a hydrocarbon fluid.
 3. The subterranean fluid production system of claim 1 wherein the recovery fluid is water.
 4. The subterranean fluid production system of claim 1 wherein the pressure within the second zone is greater than the pressure within the first zone.
 5. The subterranean fluid production system of claim 1 wherein the second zone is positioned above the first zone.
 6. The subterranean fluid production system of claim 1 wherein the first zone is positioned above the second zone.
 7. The subterranean fluid production system of claim 1 wherein the first wellbore is a primary wellbore, and the second wellbore is a secondary, lateral wellbore.
 8. The subterranean fluid production system of claim 1 wherein the first flow path portion is disposed uphole of the second flow path portion.
 9. The subterranean fluid production system of claim 1 wherein the well further includes a tubing string extending through the first wellbore, and the first and second flow path portions, respectively, are at least partially defined by first and second longitudinal sections of the tubing string.
 10. The subterranean fluid production system of claim 1 wherein the well further includes a pump operatively connected in the second flow path portion.
 11. The subterranean fluid production system of claim 1 wherein at least a portion of the routing system is remotely controllable.
 12. The subterranean fluid production system of claim 9 wherein the tubing string and the first wellbore define an annulus therebetween, and the well further includes a sensor structure operative to sense the temperature and pressure in the annulus and the interior of the tubing string.
 13. The subterranean fluid production system of claim 12 wherein at least a portion of the routing system is automatically controlled in response to an output of the sensor structure.
 14. A subterranean fluid production system comprising: a first subterranean zone containing a recoverable production fluid and having a first internal pressure; a second subterranean zone containing a recovery fluid and having a second internal pressure higher that the first internal pressure; and a single well capable of simultaneously transporting production fluid from the first zone to the surface and using recovery fluid from the second zone to increase the first internal pressure and thereby increase the production rate of the production fluid in the first zone, the single well including: a first wellbore communicated with the first and second zones, a second wellbore intersecting the first wellbore and communicated with the second zone, and a routing system operative to selectively flow production fluid from the first zone to the surface sequentially through the second and first wellbores, and to selectively flow recovery fluid from the second zone to the first zone through the first wellbore.
 15. The subterranean fluid production system of claim 14 wherein the production fluid is oil.
 16. The subterranean fluid production system of claim 14 wherein the recovery fluid is water.
 17. The subterranean fluid production system of claim 14 wherein the second zone is positioned above the first zone.
 18. The subterranean fluid production system of claim 14 wherein the first zone is positioned above the second zone.
 19. The subterranean fluid production system of claim 14 wherein at least a portion of the routing system is remotely controllable.
 20. For use in conjunction with a subterranean region having disposed therein a first zone containing a recoverable production fluid, and a second zone containing a recovery fluid, a single well useable to simultaneously produce production fluid from the first zone while utilizing recovery fluid from the second zone to increase the pressure in the first zone and thereby increase the well production rate, the single well comprising: a first wellbore extending through the first and second zones; a tubing string extending through the first wellbore and defining therewith an annulus circumscribing the tubing string; a longitudinally spaced plurality of sealing structures circumscribing the tubing string, disposed in the annulus and forming first and second sealed off annulus intervals therein, a third interior portion of the first wellbore being disposed downhole of the first and second annulus intervals and communicated with the interior of the tubing string; a second wellbore extending outwardly from the first wellbore and intercommunicating the first annulus interval with the first zone; a first valve connected in a portion of the tubing string disposed within the first annulus interval and operable to selectively communicate the interior of the tubing string with the first annulus interval; a second valve connected in a portion of the tubing string disposed within the first annulus interval downhole from the first valve, the second valve being operable to selectively permit and preclude fluid flow through the tubing string past the second valve; a third valve connected in a portion of the tubing string disposed within the second annulus interval, the third valve being operable to selectively communicate the interior of the tubing string with the second annulus interval; a first sidewall opening formed in the first wellbore at said second interval and intercommunicating one of the first and second zones with the second interval; and a second sidewall opening formed in the first wellbore and intercommunicating the other of the first and second zones with the third interior portion of the first wellbore.
 21. The single well of claim 20 wherein the production fluid is oil.
 22. The single well of claim 20 wherein the recovery fluid is water.
 23. The single well of claim 20 wherein the first valve is a production interval control valve.
 24. The single well of claim 20 wherein the second valve is a production/dumpflood isolation control valve.
 25. The single well of claim 20 wherein the third valve is a dumpflood control valve.
 26. The single well of claim 20 further comprising a pump operatively installed in a portion of the tubing string disposed in the second interval.
 27. The single well of claim 26 wherein the pump is operative to pump fluid through the tubing string in a downhole direction.
 28. The single well of claim 26 wherein the pump is operative to pump fluid through the tubing string in an uphole direction.
 29. The single well of claim 20 wherein the first, second and third valves are remotely controllable.
 30. The single well of claim 20 further comprising a sensor structure operative to sense the pressures in the second annulus interval and within the tubing string downhole of the second valve.
 31. The single well of claim 20 further comprising a sensor structure operative to sense the temperatures in the second annulus interval and within the tubing string downhole of the second valve.
 32. A method of producing fluid from a first subterranean zone at a rate accelerated using fluid from a second subterranean zone, the method comprising the steps of: extending a primary wellbore through the first and second zones; extending a secondary wellbore from the primary wellbore into the first zone; flowing fluid from the first zone to the surface sequentially through the second and first wellbores; and flowing fluid from the second zone into the first zone through the first wellbore.
 33. The method of claim 32 wherein the step of flowing fluid from the first zone includes the step of remotely controlling the flow of fluid from the first zone into the first wellbore.
 34. The method of claim 32 wherein the step of flowing fluid from the second zone includes the step of remotely controlling the flow of fluid from the second zone into the first wellbore.
 35. The method of claim 32 wherein the step of flowing fluid from the second zone is performed by pumping fluid from the second zone into the first zone through the first wellbore.
 36. The method of claim 32 wherein the pressure in the second zone is higher than the pressure in the first zone, and the step of flowing fluid from the second zone is performed utilizing the pressure differential between the first and second zones.
 37. A water dumpflooding-enhanced hydrocarbon production method utilizing a single well and comprising the steps of: forming intersecting first and second wellbores; communicating the first wellbore with an oil-containing subterranean zone and a subterranean aquifer; communicating the second wellbore with the oil-containing subterranean zone; flowing oil to the surface sequentially through the second and first wellbores; and increasing the pressure in the oil-containing zone by forcing water from the aquifer into the oil-containing zone through the first wellbore. 